In performing infusion into a patient or in other similar situations, an indwelling needle connected to an infusion line is made to puncture a patient's blood vessel and indwell in situ, so that the desired operation can be conducted.
An indwelling needle (indwelling needle assembly) includes a hollow outer needle used as a peripheral vein catheter, an outer needle hub firmly attached to the proximal end (base end) of the outer needle, an inner needle which is inserted in the outer needle and which has a sharp needlepoint at the distal end (tip) thereof, and an inner needle hub firmly attached to the proximal end of the inner needle. An example is disclosed in Japanese Patent Laid-open No. 2009-232916.
At the time of puncture of a patient's blood vessel by the indwelling needle, the puncturing operation is conducted in an assembled state wherein the inner needle is inserted in the outer needle and the needlepoint of the inner needle protrudes from the distal end of the outer needle.
When the needlepoint of the inner needle has reached the inside of the blood vessel, blood flowing in via an opening at the needlepoint passes through the lumen of the inner needle, and flows into the inside of the transparent inner needle hub (flashback). This helps enable the operator to confirm (visually confirm) that the inner needle has securely punctured the blood vessel.
After confirmation of the flashback, the outer needle is advanced, with the inner needle as a guide, and the outer needle is inserted into (made to puncture) the blood vessel.
Next, the inner needle is pulled out of the outer needle, a connector of the infusion line is connected to the outer needle hub, and an infusion liquid is dispensed.
Meanwhile, as a catheter which is longer than the above-mentioned peripheral vein catheter and is placed indwelling into a patient's blood vessel for dosing the patient with an infusion, for example, a central vein catheter, a PICC (Peripherally Inserted Central Catheter), a midline catheter and the like.
In order to put such a catheter indwelling in a patient's blood vessel, first, an introduction needle is made to puncture the patient's blood vessel. The puncture by the introduction needle is conducted by using the outer needle as the introduction needle. Then, the catheter is fed into the introduction needle, which places the catheter indwelling in the patient.
However, the procedure of indwelling the above-mentioned catheter in a blood vessel is relatively more complicated than the procedure of indwelling the above-mentioned outer needle in the blood vessel.
The lengths of the inner needle and the outer needle of the indwelling needle assembly can be selected to be large and to use the outer needle as the central vein catheter, PICC, or midline catheter.
When the lengths of the inner needle and the outer needle are selected to be relatively large, however, at the time of a puncturing operation, the inner needle and the outer needle may be deflected, making the puncturing relatively difficult. For example, where the inner needle is relatively thin and the inner needle and the outer needle are relatively easily deflected, it can be relatively difficult to achieve puncture.